How Stuff Works --
About 200 mostly short, concise articles explaining the function and/or design
of machines and apparatus. Also gives explanations of various concepts and
processes that you likely have wondered about at one time or other.
http://www.howstuffworks.com

AllCrafts --
Has instructions for a variety of make-it-yourself craft items. I like the paper boats.
www.allcrafts.net/

Creativity Portal --
Has links to craft sites, some how-to articles mostly on decorative crafts, some articles on topics such as creativity, writing, and the business of crafts.
www.creativity-portal.com